All data live in streams
Timeplus is a streaming analytics platform and data lives in streams. Timeplus
streams are similar to
tables in the traditional SQL databases. Both of them are essentially datasets. The key difference is that Timeplus stream is an append-only (by default), unbounded, constantly changing events group.
Timeplus supports multiple types of streams:
- By default, the streams are append-only and immutable (older data can be purged automatically by setting a retention policy).
- If you want to create a stream to track the latest value for a primary key, you can create Changelog Streams. It works great with CDC(Change Data Capture) data sources, such as Debezium for PostgreSQL, MongoDB or other databases. The INSERT, UPDATE, DELETE operations can be converted to update to the Changelog Stream, and you can always get the latest row for any primary key.
- You can also create Versioned Streams if you need to keep more than the latest value. When you run SQL to join an append-only stream with such a versioned stream, Timeplus will automatically use the version with the closest timestamp to match the append-only stream.
- You can also define External Streams to run SQL against remote Kafka/Redpanda brokers.
Create a stream
In most cases, you don't need to explicitly create a stream in Timeplus. When you ingest data into Timeplus from Kafka or file sources, streams can be created automatically to match the schema of the data.
The rest of this page assumes you are using Timeplus Console. If you are using Proton, you can create the stream with DDL. Learn more
Query a stream
By default, querying the stream will continuously scan new events and output new results. It never ends unless the user cancels the query. For example, you can get the latest web logs with HTTP 500 error or get the min/max/avg of a metric for every minute from an IoT device. Please read Streaming Queries for more details.
If you only want to analyze the existing data and need an immediate response, you can run Non-streaming Queries via the table function. This will turn the query in the bounded mode and only scan the existing data. For example, you can run
select count(*) from table(stream1) to get the total number of rows in the data stream.
Delete a stream
From the web console, you can delete the stream. This will permanently delete all data in the stream and delete the stream itself. Data cannot be recovered after deletion.